Bending apparatus for bending a marginal flange on a workpiece

ABSTRACT

Apparatus for bending a margin flange (5), which projects at an angle to a surface on a workpiece (2), against the workpiece. The apparatus includes a bending tool (6) which is mounted on a tool holder (14) carried by a parallelogram mechanism (7-12) for movement in relation to a stand (1) on which the workpiece (2) is placed. A drive arrangement (17) is drivingly connected to the tool holder (14) by a linkage (21-27). The tool holder (14) includes a main part (13) connected to the parallelogram mechanism (7-12) and a movable part (15) which is pivotal about a journal pin (16) on the main part. The journal pin (16) is substantially parallel with the axes (7, 8, 11, 12) of the parallelogram mechanism. The movable part (15) carries the tool (6) and by a resilient element (32) is urged towards a starting position with a nose of the tool (6) biased away from the workpiece (2). The linkage (21-27) includes a projection (28) for co-action with an abutment (29) on the movable part (15) of the tool holder (14) in one position of the linkage (21-27) to cause the movable part (15) of the tool holder (14) to move away from the starting position, the main part (13) of the tool holder (14) thereby being located in the vicinity of an end position in which the tool (6) is in engagement with the margin flange (5) on the workpiece (2).

The present invention relates to apparatus for bending a margin flange,which projects at an angle to a surface on a workpiece, against saidworkpiece, the apparatus including a bending tool which is mounted on atool holder carried by a parallelogram mechanism for movement inrelation to a stand on which the workpiece is placed, and furtherincluding a drive arrangement which is drivingly connected to the toolholder, by means of a linkage.

Apparatus of this kind are previously known in various forms. Suchapparatus are used, for instance, to bend a margin flange on a sheetmetal workpiece around the margin of another sheet metal workpiece, toeffect a clinching or hemming joint which joins the two workpiecestogether. This type of operation is common, for instance, within thevehicle manufacturing industry, in the production of different vehiclebody parts. One drawback with such known apparatus, however, is that arelatively large free area is required around the margin flange to bebent, in order for the apparatus to function satisfactory. This makes itdifficult, or even impossible, to use such apparatus for certain kindsof working operations where said space is extremely limited.

One example of an apparatus of the above mentioned kind is known fromGB-A-958671. This previously known apparatus has the drawback thatrather large parts of the apparatus are situated both above and belowthe margin flange to be bent. Therefore, this known apparatus requires alarge free space around the margin flange to be bent, and it cannot beused to bend margin flanges in confined spaces.

The object of the invention is to provide apparatus of the aforesaidkind which do not suffer these drawbacks and which can also be used inconfined spaces with satisfactory results. This object is achieved inaccordance with the invention in that the tool holder includes a mainpart which is connected to the parallelogram mechanism, and a movablepart which is pivotal about a journal pin on the main part, said journalpin being substantially parallel with the journal pins of theparallelogram mechanism; in that the movable part carries the tool andby means of a resilient element is urged towards a starting positionwith the nose of the tool biased away from the parallelogram mechanism;and in that the linkage is a toggle linkage which includes a projectionfor co-action with an abutment on the movable part of the tool holderwhen the toggle linkage is in the proximity of its fully extended stateto cause the movable part of the tool holder to move away from thestarting position, the main part of the tool holder thereby beinglocated in the vicinity of an end position and the tool being inengagement with the margin flange on the workpiece.

The invention will now be described in more detail with reference to theaccompanying drawings, in which FIG. 1 is a somewhat schematic side viewof one embodiment of the inventive bending apparatus;

FIG. 2 is a schematic side view of the apparatus of FIG. 1, and showsthe apparatus components in their respective starting positions, priorto commencing a working sequence;

FIG. 3 is a schematic side view of the apparatus of FIG. 1, and showsthe apparatus components in their respective preliminary bending orpre-form positions, during a working sequence; and

FIG. 4 is a schematic view of the apparatus of FIG. 1, and shows theapparatus components in their respective final bending or clinchingpositions during a working sequence.

The apparatus illustrated in FIG. 1 comprises a stand 1 which is mountedon a support surface (not shown), which also supports a workpiece 2. Theillustrated workpiece 2 comprises a sheet metal rail 3, in which a sheetmetal profile section 4 is placed. The sheet metal rail 3 has two marginflanges 5, of which one flange is shown in FIG. 1 to be bent over alower flange on the sheet profile section 4. Binding of the flange hasbeen effected with the aid of a tool 6.

The stand 1 carries two journal pins 7 and 8 which are mutuallyparallel. Respective one ends of pivot arms 9 and 10 are journalled on arespective journal pin 7 and 8, and the other ends of the arms 9 and 10are journalled on a respective journal pin 11 and 12. The journal pins11 and 12 are carried by a main part 13 of a tool holder 14, which inaddition to said main part 13 also includes a movable part 15, which ispivotally mounted on a journal pin 16 carried by the main part 13.

The spacing between the journal pins 7 and 8 is equal to the spacingbetween the journal pins 11 and 12, and the pivot arms 9 and 10 are ofmutually equal lengths, and consequently the members 7-12 form aparallelogram mechanism. Consequently, the tool holder 14 can be movedrelative to the stand 1, with the aid of the parallelogram mechanism7-12. The movable part 15 of the tool holder 14 carries the tool 6,therewith enabling the tool 6 to be moved towards and away from theworkpiece 2, when the tool holder 14 is moved with the aid of theparallelogram mechanism 7-12.

The stand 1 also carries a drive arrangement for effecting movement ofthe tool holder 14. This drive arrangement includes a pressure-mediumoperated piston-cylinder device 17, which is pivotally connected to thestand 1 by means of journal pins 18. The outer end of the piston rod 19of the piston-cylinder device 17 is provided with an end piece 20, whichis pivotally connected to one arm 22 of a double-arm lever 23, by meansof a journal pin 21. The lever 23 is pivotally journalled on the stand 1by means of a journal pin 24.

The free end of the other arm 25 of the double-arm lever 23 is pivotallyconnected, by means of a journal pin 26, to the one end of a link 27,the other end of which is journalled on the journal pin 12 of theparallelogram mechanism 7-12, between the stand 1 and the tool holder14. The other arm 25 of the lever 23 and the link 27 therewith form atoggle linkage, which controls movement of the tool holder 14 inrelation to the stand 1. In the position of the apparatus componentsillustrated in FIG. 1, the toggle linkage 25-27 is essentially fullyextended. As will be seen from FIG. 1, a projection 28 on said other arm25 of the lever 23 will therewith abut an abutment 29 on the movablepart 15 of the tool holder 14. In this position of the apparatuscomponents, contact between the projection 28 and the abutment 29 hascaused the movable part 15 to pivot about the journal pin 16, such as tomutually separate two shoulders 30, 31 on the main part 13 and themovable part 15 respectively of said tool holder 14. This movement iseffected against the action of a spring 32, which urges a pin 33 intoabutment with the movable part 15 of the tool holder 14, such as topivot the movable part 15 in a direction towards mutual contact of theshoulders 30 and 31.

FIGS. 2-4 illustrate schematically the different positions adopted bythe apparatus components described with reference to FIG. 1 whencarrying out a working sequence. FIG. 2 illustrates the apparatuscomponents in their respective starting positions, in which the tool 6is spaced from the workpiece 2. In this position, the piston rod 19 ofthe hydraulic piston-cylinder device 17 is fully extended, andconsequently the lever 23 is rotated in an anti-clockwise directionaround the journal pin 24 to the maximum possible extent. The togglelinkage 25-27 has therewith drawn the tool holder 14, by means of theparallelogram mechanism 7-12, as far to the right as possible, when seenin the drawing. The projection 28 is spaced from the abutment 29, andthe pin 33, under the influence of the spring 32, has rotated themovable part 15 of the tool holder 14 as far as possible around thejournal pin 16 in a clockwise direction, so that the shoulders 30 and 31are in abutment with one another.

FIG. 3 illustrates the apparatus components in a position in which thetool 6 has bent the margin flange 5 of the workpiece 2 through an angleof about 45°. In order for the apparatus to have reached this operatingposition, the piston rod 19 has been withdrawn to a given extent intothe cylinder of the piston-cylinder device 17, such as to rotate thelever 23 clockwise about the journal pin 24. In conjunction herewith,the journal pin 26 of the toggle linkage 25-27 has been moved upwards,as seen in the drawing, and, at the same time, the parallelogrammechanism 7-12 has moved the tool holder 14 to the left to an extentsuch that the tool 6 has come into engagement with the margin flange 5.

FIG. 4 illustrates the apparatus components in a position in which theprojection 28 has just come into contact with the abutment 29. Thepiston rod 19 has, in this case, been withdrawn further into thecylinder of the piston-cylinder device 17, and has therewith caused thelever 23 to rotate further about the journal pin 24. The parallelogrammechanism 7-12 has therewith moved the tool holder 14 further to theleft, as seen in the drawing, so that the tool 6 has substantiallycompletely bent the margin flange 5. The shoulders 30, 31, however, arestill in mutual abutment.

In order to effect final bending of the margin flange 5 to the positionillustrated in FIG. 1, the piston rod 19 is withdrawn slightly from theposition illustrated in FIG. 4. This will cause the lever 23 to pivotslightly about the journal pin 24, so that the projection 28, with theaid of the abutment 29, will pivot the movable part 15 of the toolholder 14 about the journal pin 16, so as to press the tool 6 harderagainst the margin flange 5, to complete bending of the flange.

Subsequent to carrying out the aforedescribed working sequence, theapparatus components are returned to the starting position illustratedin FIG. 2, by extending the piston rod 19 from the cylinder of thepiston-cylinder device 17. The spring 32 and the pin 33 therewith swingthe movable part 15 of the tool holder 14 to an extent such that theshoulders 30 and 31 will abut one another. The apparatus is then readyto carry out a new working sequence.

The invention is not restricted to the aforedescribed exemplifyingembodiment thereof, since modifications can be made thereto within thescope of the following claims.

I claim:
 1. In apparatus for bending a margin flange (5), which projectsat an angle to a surface on a workpiece (2), against said workpiece, theapparatus including a bending tool (6) having a nose, said bending toolbeing mounted on a tool holder (14) carried by a parallelogram mechanism(7-12) for movement in relation to a stand (1) on which the workpiece(2) is placed, said parallelogram mechanism comprising links (9, 10)having each at one end a pivot axis (7, 8) carried by the stand (1) andat the other end a pivot axis (11, 12) carried by the tool holder (14),the distance between the stand-carried pivot axes (7, 8) being equal tothe distance between the pivot axes (11, 12) carried by the tool holder(14) and the distance between the pivot axes (7, 11) on one link (9)being equal to the distance between the pivot axes (8, 12) on the otherlink (10), a drive arrangement (17) which is drivingly connected to thetool holder (14) by means of a linkage (21-27); the improvement whereinthe tool holder (14) includes a main part (13) connected to theparallelogram mechanism (7-12) and a movable part (15) which is pivotalabout a journal pin (16) on the main part, said journal pin (16) beingsubstantially parallel with said axes (7, 8, 11, 12) of theparallelogram mechanism; the movable part (15) carries the tool (6) andby means of a resilient element (32) located on the main part is urgedtowards a starting position wherein the nose of the tool (6) is biasedaway from the stand holding the workpiece (2); said linkage including aprojection (28) for co-action with an abutment (29) on the movable part(15) of the tool holder (14) whereby in one position of the linkage(21-27), the projection contacts the abutment to cause the movable part(15) of the tool holder (14) to move away from the starting positiontowards an end position wherein the tool is in engagement with themargin flange of the workpiece, the main part (13) of the tool holder(14), by way of the parallelogram mechanism, being moved into thevicinity of the end position of the tool holder (14).
 2. Apparatusaccording to claim 1, characterized in that the drive arrangementcomprises a pressure-medium operated piston-cylinder device (17), thecylinder of which is pivotally connected to the stand (1) and thepiston-rod (19) of which is pivotally connected to the linkage (21-27).